T-maxx Direct Drive Conversion Idea

[BL_RV0]

Hey guys, my project is what you would get if lincpimp's hv maxx and sikeston34m's direct drive revo had a child. a direct drive high voltage t-maxx!
t-maxx is currently in the mail. will get some pix when i get the nitro "decoration" off.
here is my proposed setup-
this motor
https://www.unitedhobbies.com/UNITED...idProduct=5204
this esc
https://www.unitedhobbies.com/UNITED...idProduct=4691
2 of these batts, in series
https://www.unitedhobbies.com/UNITED...idProduct=2133
and 2 of these, motor has a 8mm shaft
http://www.rc-monster.com/proddetail...mrevov2coupler
most likely, 2 of these to mount the motor.
https://www.unitedhobbies.com/UNITED...idProduct=5307

the only problem is, brakes!
i basically need to retain mechanical brakes, and dont want to spend a fortune on a kontronik.
any ideas???

[Serum]

Mechanical brakes are the big catch. I would use slightly larger batteries, i've tested them on a 700 watts peakpower. so 2 of them in series are good to 1400 watts. That's not enough IMO.

[BL_RV0]

what batteries would you recommend that i can get both for under 150?

[sikeston34m]

Originally Posted by Serum

Mechanical brakes are the big catch. I would use slightly larger batteries, i've tested them on a 700 watts peakpower. so 2 of them in series are good to 1400 watts. That's not enough IMO.

I have to aggree with Serum on this one.

2200mah at 20C is only 44 amps continous, 66 amp burst.

It's going to spike quite a bit on take off.

[BL_RV0]

ok, ill use different batts. but whay about brakes?

[BL_RV0]

if this is any help
Differential Ratio: 2.8461538461538462
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 1
Pinion Tooth Count: 1
Total Voltage: 29.6
Motor KV: 270
Tire Diameter (inches): 5.75
Tire Ballooning (inches): 0
Motor Current Draw: 70
Motor coil Ω: 0
Spur/Pinion Ratio: 1 : 1
Total Ratio: 2.84615 : 1
Tire Circumference (inches): 18.06 inches (458.83 mm)
Total Motor Speed: 7992 RPM
Vehicle Speed: 48.03 mph (77.16 km/h)
Effective Speed Rate: 1.62 mph/V (2.61 kmh/V)
Estimated Adjusted Speed: 45 mph (72 km/h) - 6% loss
Effective KV Value: 270
Motor Torque: 1.83 ft-lbs
Final Torque: 5.2 ft-lbs
Final Power: 2072 watts (2.8 HP)

[sikeston34m]

The numbers look good. But...........there's always a but. LOL

That's one huge gear ratio. 2.85:1

You've chosen a lower kv outrunner. A big one, and that should help. Running it on 8S will get your top speed up to the really fun range.

You need an ESC with a great startup routine. I don't have any experience with that one. Metalman does I believe.

On the brakes, this is where you have to be creative. On my Revo, I had considered moving the mechanical brake to the diff pinion. There is a kit for the Revo that allows for this. I wonder if there is something like this available for the T maxx?

[BL_RV0]

well, i suppose i could spend <$200 on a esc, if it measn brakes or no brakes

[BL_RV0]

i suppose i could use a mgm 8024?

[BL_RV0]

or a castle hv-85?

[lincpimp]

May I suggest a diff upgrade? I would say that a pair of hybrid diffs with the buggy ratio gears would be a good idea. I do not think that the stock maxx diffs will be able to hadle the power of torque. Mech brakes would not be too difficult to do, but you would have t make a bracket to go across the chassis and hold the disk in the correct orientation and old the brake actuator.

Sounds like a fun project, make sure that you post pics! I will finish the hv tmaxx as soon as the brake linkage comes in at the lhs, been waiting 4 weeks, lol!

[BL_RV0]

well before i can start this project, i gotta get this revo that ive been offered a very good deal on.

[MetalMan]

If you haven't seen them already, check out the pics of my MT2:
http://smg.photobucket.com/albums/v1...ner%20powered/
That'll give you an idea of what can work.

The OEMRC/Turnigy ESC works well and under lighter loads doesn't really cog. Running 10s A123 and a 4020/06 (610 kv), which has a stator 10mm shorter than that Turnigy motor you linked to, it would cog pretty harshly from a dead stop if I yanked the throttle. But that's to be expected, considering that the estimated top speed is ~70-75mph (it ran out of downforce before I could find out the actual top speed).

For mechanical brakes, you'll have to custom-mount them. You'll notice I sorta ghetto-rigged mine with a piece of music wire, but it can be done to look nicer and be more effective.